Compare Revisions

winmail.dat attachment microsoft exchange outlook

When people send mail from email clients (like Microsoft Outlook) that use the Microsoft Exchange server, a file attachment called winmail.dat may be added to the message. This file contains formatting information for messages that use Microsoft's proprietary TNEF standard. The file is unrecognized by other email clients and results in any attachments in the original message not being present in the email.

When people send messages from incorrectly configured Microsoft Outlook email clients, a file attachment called {filepath winmail.dat} may be added as an attachment to the message. This file contains formatting information for messages that use Microsoft's proprietary TNEF standard and any attachments sent with the original message. The file is not recognized by other email clients. Because of this, any attachments sent with the original message are not displayed in Thunderbird's message view. If you try to open {filepath winmail.dat}, you will probably be prompted to specify the application that should be used to open the file. Because this file is in a Microsoft proprietary Outlook/Exchange format, you may not have an application installed that can decode this file and display it. Even if your system is capable of displaying the file, it does not contain any useful information. To prevent this file from being attached to messages, the sender of the message (or their system administrator) can configure various options as described in this [http://office.microsoft.com/en-us/outlook-help/recipients-receive-a-winmail-dat-attachment-HA010153018.aspx Microsoft Support Bulletin]. There is also a Thunderbird add-on called [https://addons.mozilla.org/thunderbird/addon/lookout/ LookOut] which tries to decode the TNEF attachment ({filepath winmail.dat}) and display the original attachments in Thunderbird's message view. This add-on '''is not provided or supported by Mozilla''' and its compatibility with future versions of Thunderbird is not assured. The best solution is to contact the message sender and inform them that their copy of Outlook is incorrectly configured as suggested in the Microsoft Support Bulletin. [[Template:ShareArticle|link=http://mzl.la/1fJ23lW]]